Circular Waveguide Taper of Improved Design

Transitions between round waveguides of different sizes fur TE01transmission are required to be free of mode conversion. Conical tapers with a gradual change of cone angle transform cylindrical waves in the round waveguide into spherical waves in the transition region. They thus cause very little power conversion to spurious modes. Optimal tapers and almost optimal tapers are found. An improved taper connecting 7/8 in. to 2 in. i.d. waveguide must be 3 ft long to keep the spurious mode level below — 50 db for frequencies up to 75 kmc. A taper of constant cone angle would have to be 58 ft long to obtain the same spurious mode level.